Mandrel for spinning metal



Feb; 9, 1,937. J, sQUlREs I Y 4 v l2,069,858

MAHDREL Fon sf'NNING METAL original Filed Jll-Ly 5, 1953 Zaza.

M? mym;

Ammin/'5l f Patented Feb." 9, 1937 UNITED4 STATES PATENT oFF-ICEOriginal *application July 5,

1933, serial No.

679,133. Divided and this application April 2,

' 1934, Serial No. 718,573

(Cl. ID3- 52) 7 Claims.

.This invention relates to apparatus for spinmng metal and hasparticular relation to closing the open end of a tubular blank forairplane propeller blades, and is a division of my application 6 forLetters Patent of the United States for Improvementsv in propeller bladeand method and apparatus for producing same, led July 5, 1933, SerialNo. 679,133. Objects' of the invention include the provision 10 of animproved apparatus for closing the end of a tubular object byv aspinning operation; the provision of an improved mandrel for useinternally of aA tube during' the operation of closing an end of thetube by a spinning operation; the provision of an improved type ofmandrel for use internally of a tube the end of which is'to be closed bya spinning operation while the tube is in heated condition, and soconstructed as to minimize the transfer of heat away from the end of thetube to be closed during the spinning operation; the provision of a.mandrell adapted to internally support the end of a propeller blade'blank during a spinning operation thereon to close such end; theprovision oa mandrel adapted for insertion within theend of a hollowpropeller blade blank during a spinning operation to close such endwhile such end is in a heated condition and so constructed and'arrangedas to minimize the transfer of heat'from such end -to the mandrel; theprovision of a mandrel for internal use within the end of avhollowpropeller blade blank during the operation of spinning the end of theblank closed, the mandrel being formed with a portion to control theinternal shape of the spun end portion of the blank and another-.portion for centering the mandrel in the blank y and reinforcing theblank internally against the application of pressure -from the outside;and the provision of a mandrel for a spinningvoperation comprising amain body portion corresponding in size, shape and contour to theinterior walls of a portion of a tube to be received thereon, and anadditional portion so constructed and formed that it has a relativelylimited additional contact with the interior walls of the tube.

The above being among the objects of th present invention, the sameconsists in certain novel features of construction and combinations ofparts to be hereinafter described with reference. to the accompanyingvdrawing, and then claimed, having the above and other objects in view.

In the accompanying drawing which illustrates a suitable embodiment ofthe presentv invention 'tioned side elevational viewl of a blank for anair- 'plane propeller blade.

and in which like numerals refer to like parts l throughout the severaldifferent views,

, Figure 1 is a' partially broken, partially sec- Fig. 2 is a verticalsectional View taken transversely through the axis of the blank shown inFig. 1 as on the line 2-2 of Fig. 1.'.

Fig. 3 -is an enlarged fragmentary sectional view of the small end ofthe blank shown in Fig. 1 10 and illustrating in part the apparatusemployed for closing the small end of the blank and before suchapparatus has acted upon such small end.

Fig. 4 is a view similar to Fig. 3 but illustrati ing in greater detailthe apparatus employed in 15 the closing of the small end of the blankand i1- lustrating the small end of th blank after 'one of the initialclosing operations thereon.

Fig. 5 is a view similar to Fig. 3 and illustrating the small end of theblank after a further 20 closing operation thereon.

Fig. 6 is a view similar to Fig. 5 and showing the small end of theblank after it has been completely closed.

Inone method of forming airplane propeller 25 blades as brought out indetail in the above referred to application of which the presentapplication is a division, a cylindrical metal tube is acted upon toprovide an outwardly projecting annular ang'e at one end and an inwardlyta- 30 peredend or nose at the opposite end. The tube is then subjectedto suitable machining and/or other operations to predetermine itsinternal and external size, shape and contour and preferably to reducethe Wall thickness thereof from the 35 flanged end toward the small ornose end thereof without changing the cross-sectional shape of theblank. The smaller tapered end of the blank is then closed, and theblank is then placed between suitable dies and suitably acted upon tochange 40 its cross-sectional shape to that desired in the nishedproduct. The present invention dealsk solely with the closing of thesmall end of such' a blank. v

Referring now to Figs. 1 and 2, a blank such 45 as that above describedis illustrated in a condition where its interior and exterior surfaceshave been formed to predetermined size, shape and contour and ascomprising a main body portion H2 having at one end thereof a shank por-50 tion |04 and ilange |06 and the opposite end thereof being graduallytapered as at |34 to form a small end or nose without completely closingsuchend. The radially extending outwardly projecting annular flange |06in the particular ex-7 55 ample shown is provided for the purpose ofper-V mitting the ultimate blade to be secured to a hub structure. Theshank portion |00 varies from a maximum thickness adjacent the-nange |00to a minimum thickness at its opposite end where -it merges into themain body portion |I2 in a smooth curve and acts to provide addedrigidity and strength to this portion of the blade.

The wall thickness'of the main body portion Ii preferably decreasesin'thlckness from its point of connection with its'shank portion i tothe nose or small end thereof and this) feature is shown in the drawing.It will be understood that the entire blank is circular in cross sectionfrom end .to end as indicated in Fig. 2 and that the small end of the,blank is not completely closed initially, in order to permit greaterease in the machining, for instance, of both lthe interior and exteriorsurfaces of the blank. I

After the blank hasreached the stage of completion indicated in Figs.-1and 2 and as described, the'next operation is to close the nose` orsmall end |34 of'the blank H2 and this is preferably accomplished by theuse of a spinning operation such as is indicated in Figs. 3 to 6, in-

clusive. a a

In connection with the closing of the small end of the blank, it hasbeen found desirable, although not necessary inall cases,.andparticularly where the tip is relatively small, to increase the wallthickness of the blank at the extreme closed end portion thereof andalso, although not necessary in all cases, to.provide a projectingnipple about -the point of closure for the reason that during pressingof the blank to blade shape a considerable amount of bending andstretching of the metal in the extreme endportion occurs, and ess asuitable amount of metal is provided at s` point, particularly where thesmall end of the blank is not relatively small, a crack isliable todevelop in the finished article. l

In carrying out this spinning operation ithe blank l|2 is placed upon amandrel indicated at 200 in Figs. 3 to 6, inclusive. This mandrel 200does not necessarily need to contact with the interior walls of theblank H2 over the full length of the blank but in any case must have anend portion 202 which accurately nts and is properly centered in theinner end portion of the nose i of the blank. The extreme end of theportion 202 is rounded as at 200 into exact conformance with thatdesired for the interior surface of the end of the ilnished blank.Preferably, the end sur- 'contact with the mandrel.

center located as at 206. After the mandrel 20| has been thus formed itis preferable to cut it down or relieve it in diameter toward the tip.'I'his relief, whichv is indicated at 202a, may begin a little over aninch'back from the 'tip and need not be very deep, as little as 5thousandths of an inch having been found satisfactory. The purpose ofthis cut is to keep a material area of the end of the blank from actualand thermal It has been found that when the end of the blank is incomplete contact with the corresponding portion of the mandrel it isdiillcult to keep the end of the blank hot enough to be conveniently andproperly worked. lBy cutting out the mandrel as shown the blank is keptfrom contact therewith except at such locations as arenecessary to theproper forming of the interior shape of the end of the blank during theclosing operation and for the 'proper support of the end of the blankwithout -distortiomas will later be brought out, and the heat is not soreadilyloonductea away from the portion of the blank which is to bespun.

The mandrel 200 with the blank II2 thereon is then mounted in a suitablelathe lor other turning machine which may include, as indicated in Pig.4.a bed 203 upon which is longitudinally movable a main slide 2I0 uponwhich is a compound slide 2|2. The nose end of the blank may be suitablysupported as by a steady rest 2M, care being taken in adjusting it toallow for anyv I subsequent expansion of the blank which may occur dueto heatingthe tip thereof for the spinning operation. The steady rest 2I0 is preferably v*located in alignment with that portion of the end202lof the mandrel which has not been cut out so that undue pressure of thesteady rest on the exterior of the blank will not distort the blank. Astop 2li, as indicated in Fig.'4, is preferably provided for engagementwith the slide 2i! so as to limit movement yof the carriage 2li f andconsequently the pivotal axis 2 I l of the compound slide 2i2 to theleft asvviewed in the ngure. The stop 2i0 is preferably adjusted andfixed so that the pivotal center 2|. of the compound carriage 2 I2, andconsequently the spinning tool 220 carried thereby, may be limited inits approach 'toward the center 200 of the end surface 204 of themandrel by a distance indicated .in Fig. 3 at 222 equal to the addedwall thickness desired for the extreme tip portion of the blank H2. i Inoperation, and referring now to Fig. 4, the mandrel 200 and yblank |I2are rotated inthe lathe and llame from a torch such as '224 is playedupon the end portion of the blank |I2 to l bring it to `a suitablecondition of plasticity as," for instance that indicated by a bright redcoloring ofl the metal at the nose or tip. 'Ihe carriage 2li is moved tothe right until the pivotal Y axis 2|! ofthe cross slide SI2 is spaced adistance s uch as 220 outwardly from its predetermined final -positionas determined by the stop 2 I0, and the spinning tool 220 is thenbrought toa position such that when it is swung about the axis 2|. itwill engage only the extreme endportion of the no |34 of the blank H2.lAs soon as the heat from the ilame of the torch 220 has brought theextreme end portion of the blankv to a sumcient condition' ofplasticity,V as above described,

the compound carriage 2I2 and the tool 220 carried thereby is swungabout the axis 2I0, preterably in a counter-clockwise direction asviewed `in Fig. 4, and thetool 220 thus coming in con tact with theextreme end portion of the nose or tip causes it to be spun in asindicated in Fig. 4. The main'slide 2li is then moved a short distanceto the left, asviewed in the flgures,'until the distance 220-in Fig. 4has been reduced, for instance, to a distance indicated at 228m Fig. 5at which time the tool 220 is again `swung aroundlthepivotalaxis2I0tospin theextreme tip of the blade furtherinwardly asindicated in Fig. 5.

This movement of the main slide 2ll"carrying with it thespinning tool220 is repeated as many times as is desirable or n, taking care thateach'pass of the tool 22| is an "easy" pass llsoastoinsureasmoothilowofthemetaloi'the possible. An excess-of metal isprovided in the end of the blank so that the tip wall may be .somewhatthicker than the immediately adjoinduring these operations and may keepsuch end at such temperature that when the end isiinally closed, asindicated in Fig. 6, the metal of the tip may weld itself together atthe line or point of closure.

The thickened end portion surmountedF by the nipple, 230 reinforces theend of the blank so that it may not break open under the stresseslproduced when the blank is deformed into the blade form in the pressingdies employed in subsequent operations. Upon completion ojthe closingoperations on the end of the blank the newly closed end portion of theblank is preferably polished and buied so as to bring it to the samecondition of nish as the main body portion of the blank.

Formal changes may be made in the specific embodiment of the inventiondescribed without departing from the spirit and substance of the broadinvention, the scope of which is commensurate with the appended claims.

I claim:

1. A mandrel for supporting a tube to be heated and spun closed at itsend comprising a base portion snugly fitting the interior of the tube, a

body portion slightly smaller than the interior of the surroundingportion of the tube and adaptedv to be spaced therefrom throughout thespinning' operation to reduce transfer of heat between the tube and themandrel; and an end of thesize and shape desired in the interior of thetip of the closed tube.

2. A mandrel foruse internally of a tube during a closing operation upona heated end thereof comprising a member adapted to t internally of saidtube adjacent said end thereof, an end of said meniber being shaped tocontrol the internal shape of said end when closed, and said memberbeing radially relieved axially between its ends to provide spaced zonesof contact with the interior walls of said tube.

3. A mandrel for use internally of a tube during a closing operationupon a heated end thereof comprising a member so constructed andarranged' as to provide axially spaced contact zones for the interiorwalls of said tube and an intermediate portion relieved against contactwith the tube during the closing operation to reduce transfer of heatbetween the tube andthe mandrel, one ofsaid zones adapted to control theinterior shape of said end during said closing operation.

4. A mandrel for use internally of a tube during a closing operationupon a heated end thereof comprising a, member having a portion adaptedto contact the interior walls of said tube to locate it therein, anotherportion spaced therefrom providing a form for the internal surfaces ofsaid end when closed thereon, and a'portion intermediate the two rstmentioned portions adapted to provide a relief between the tube and themandrel during the spinning operation.

5. *A mandrel for use internally of the tapered end of a tube during aclosing operation on the end thereof comprising a portion externallyconforming in size, shape and contour to the interior surfaces of aportion of said end and an axially spaced portion adapted for initialcontact withv a limited length only of the interior walls of said end ofsaid tube, the last mentioned portion being shaped to provide a form forsaid end during the closing operation thereon, and said member beingradially relieved between said portions.`

6. A mandrel including a pair of axially spaced portions one of whichapproximates a frustrum v of a cone and the other of which is providedwith

